A silica glass crucible is used for growing a silicon single crystal. For example, the silicon single crystal is produced by heating and melting polycrystalline silicon charged into the silica grass crucible to obtain silicon melt, dipping a seed crystal into the silicon melt, and pulling the seed crystal upwards. During the growth of the silicon single crystal, if bubbles adhering to an inner surface of the silica glass crucible or generated float up and adhere to the silicon single crystal, the bubbles are taken into the silicon single crystal to form air pockets.
In recent years, influence exerted by the air pocket in a silicon wafer on a semiconductor device has been quite serious. The influence of the air pockets is varied depending upon their magnitudes, the number of the air pockets, locations where the air pockets are generated, and the type of a semiconductor device. However, since a size of the air pocket is very larger than that of COP (Crystal Originated Particle), no device can be formed in a space of the air pocket. Especially when the number of air pockets in a wafer is high, yield of the semiconductor device is considerably deteriorated and thus, the wafer itself must be discarded. It is therefore necessary to reduce a possibility of the air pockets existing in the wafer as close to zero as possible.
Japanese Patent Application Laid-Open No. 2001-519752 shows that Ar components of bubbles included in a crucible are taken into a silicon single crystal to form air pockets. Japanese Patent No. 3046545 shows that Ar gas which was taken in when polycrystalline silicon is melted adheres to an inner surface of a crucible, and when a silicon crystal is grown, the Ar gas is taken into the silicon single crystal. As a cause of air pockets, in addition to the Ar gas, SiO gas generated by a reaction between a silica glass crucible and a silicon melt may be taken in.